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Mitral Annulus Disjunction Arrhythmic Syndrome
Study Questions:
What are the clinical features and ventricular arrhythmias associated with mitral annulus disjunction (MAD)?
Methods:
One hundred sixteen patients (mean age 49 years) with abnormal atrial displacement of the mitral valve demonstrated by echocardiography underwent cardiac magnetic resonance imaging (CMRI). A severe arrhythmic event was defined as prior cardiac arrest or sustained ventricular tachycardia (VT). A ventricular arrhythmia (VA) was defined as a severe arrhythmic event or nonsustained (VT).
Results:
The most common symptom was palpitations (71%); 41% and 13% of patients had presyncope or syncope, respectively. A VA was present in 34% and a severe arrhythmic event in 12%. The mean maximum longitudinal MAD displacement by CMRI was 7.9 mm. Mitral valve prolapse (MVP) was present in 78% of patients. There was no relationship between VAs and MVP. Severe arrhythmic events were associated with younger age (37 vs. 51 years), lower ejection fraction (51% vs. 57%), and a higher prevalence of papillary muscle fibrosis (36% vs. 9%).
Conclusions:
VAs are common in patients with MAD regardless of whether or not MVP also is present.
Perspective:
The study demonstrates that although there is a large degree of overlap between MAD and MVP, MAD is associated with VAs independent of MVP. The findings suggest that the papillary muscles could be the source of VAs in at least some patients with MAD. Papillary muscle arrhythmias have a right bundle branch block morphology and a variable axis, with some electrocardiographic features (e.g., qR in lead V1) that may be helpful in distinguishing them from VAs arising at the mitral annulus, left posterior or anterior fascicle, and right ventricular outflow tract. Unfortunately, the study provides no information on the QRS morphology of the VAs in patients with MAD. In addition, the appropriate treatment of VAs less severe than sustained VT or cardiac arrest in patients with MAD is unclear.
Clinical Topics: Arrhythmias and Clinical EP, Cardiovascular Care Team, Noninvasive Imaging, Valvular Heart Disease, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Echocardiography/Ultrasound, Magnetic Resonance Imaging, Mitral Regurgitation
Keywords: Arrhythmias, Cardiac, Bundle-Branch Block, Diagnostic Imaging, Echocardiography, Heart Arrest, Mitral Valve Insufficiency, Mitral Valve Prolapse, Magnetic Resonance Imaging, Papillary Muscles, Stroke Volume, Syncope, Tachycardia, Ventricular
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